In my experience none of the federated platforms handle video well, especially the facebook like platforms. They are built around things being public, and expect you to upload to youtube or some other video site in order to post a video. If they let you upload videos at all, it's as an attachment. Admittedly HumHub is a bit like that, but it's not too janky from a user experience perspective.

One thing I liked about Zusam is the automatic resizing of videos to make them reasonably sized. If I record a 2 minute video, it can be 300 or 400MB. Zusam can be configured to resize the video to a set maximum size in order to make it more reasonable for people watching. HumHub doesn't do this, but I have wondered if I could use a cron job and ffmpeg to do it.

Do you want this social media to be for your family to use only with family members or for them to use with family and beyond?

I haven't decided yet. Initially we'd start with people who know our kids. But if some of those people wanted to set up a page for their own kids, they wouldn't want some of the people on our page who they don't know. And they might want people on their page that don't know our kids. So then all the HubHub privacy settings come in handy where people can create a space and control who can see what.

Revolt could be good as a local family group chat if you like the discord style.

I don't really think that's something that will be familiar enough to people, especially grant parents and other family of that generation. And I don't think a group chat is what I'm after, self hosting a group chat doesn't seem to have many advantages over say a Signal group chat.

You’ve probably already tried it but Pixelfed/mastodon/misskey sound like the easiest to get family on board with and seem like they would be good family social media platforms IMO.

These are generally public, and even if you have it set up as a private instance with no federation then it still feels like a shouting at the void kind of platform. None of the family I have in mind use twitter or mastodon, but everyone uses facebook. So I'm aiming for that sort of a feel. But IMO Friendica is not something I feel is good enough yet from a user experience point of view, the same with Diaspora*.